1. Technical Field
The present invention relates to a lifter structure including a reciprocally slidable cylindrical member provided in a guide hole of a lifter guide.
2. Related Art
Japanese Patent Application Publication No. JP-A-2012-2115 discloses a lifter structure which is suitable for use with an internal combustion engine such as automobile engines. The disclosed lifter structure includes a lifter body and a roller which abuts against a cam thereby to be pressed. The lifter body includes a cylindrical portion having an outer periphery reciprocally slidable on an inner periphery of a cylinder (a lifter guide) and a pair of supports formed to be connected to one end side of the cylindrical portion. A shaft support pin has two ends fixed to the supports respectively. The roller is rotatably supported on the shaft support pin.
The cylindrical portion has a stopper formed integrally with the one end thereof and preventing rotation of the lifter body. The stopper is slidably fitted into a stop groove recessed in the inner periphery of the cylinder.
In the lifter structure of the above-described type, a predetermined gap is defined between the outer periphery of the cylindrical portion and the inner periphery of the cylinder in order that a smooth reciprocal movement of the lifter body may be secured. The lifter body is sometimes tilted within the range of the gap when pressed by the cam. If the lifter body is tilted to a large degree, diagonal corners of the cylindrical portion are brought into biased contact with the inner periphery of the cylinder (what is called cocking phenomena) with the result that an abnormal noise is produced and there is a possibility that the cylinder may be worn by sliding.
In view the above-described problem, if the cylindrical portion is extended in the reciprocal direction so that the reciprocal sliding distance is increased, the cylindrical portion would be unlikely to tilt in the cylinder and the cocking could be reduced. In this case, however, the stopper is located at the end of the cylindrical portion in the extension direction. Accordingly, consideration should be made to prevent the stopper from intruding into a rotation locus, with the result that a sufficient sliding distance cannot be ensured.
Furthermore, since the stopper integrally protrudes outside the cylindrical portion, it is difficult to feed the cylindrical portions in one way for continuous processing in a feedthrough manner when outer peripheries of the cylindrical portions are ground in a finish processing.